The present invention relates generally to the field of wireless telecommunications, and more particularly to a method of and system for delivering calls to a mobile unit in a wireless telecommunications system with improved call setup time.
Wireless telecommunications services are growing at a tremendous rate. Users have embraced the concept of having a telephone that is with them all the time. Mobile telecommunications systems provide users with the ability to receive telephone calls, faxes, pages, and short messages at virtually any location in the country. The development of general packet radio service (GPRS) system will enable users to receive high-speed data in wireless environment, and thereby access the Internet or other data networks from virtually any location.
One of the drawbacks associated with wireless telecommunications is the relative slowness of call delivery. In order to terminate a call to a mobile unit, a substantial amount of signaling is required. The termination time is increased when the mobile unit has roamed outside its home area. The mobile unit must be located and the call must be setup over multiple system links. Termination time is even slower in the case of GPRS terminations. In GPRS systems, the mobile unit is paged on a packet control channel (PCCH), which is the control channel associated with the data session side of the system. When the mobile unit is paged on the PCCH for a telephone call, the mobile unit must retune to the digital control channel (DCCH) in order to respond to page and proceed with call setup. In addition to the time spent retuning, there is a substantial amount of additional signaling associated with terminations of calls in a GPRS system.
Callers to mobile units may find the slow setup time annoying. Callers may even believe that an error has occurred and that the call will not be completed at all. Accordingly, it is an object of the present invention to provide a system and method for reducing the time required to complete calls to mobile units.
The present invention provides an improved method of and system for delivering a call to a mobile unit in a wireless network. The system includes a mobile switching center that receives a call setup request message initiated in response to a request from an originating mobile switching center. The receiving mobile switching center initiates setting up the call between the receiving mobile switching center and the mobile unit before completion of call setup between the receiving mobile switching center and the originating mobile switching center. Preferably, the receiving mobile switching center initiates setting up the call by issuing a page in response to receiving the call setup message.
The present invention is broadly applicable to all wireless telecommunications systems. For example, the receiving mobile switching center may be a serving mobile switching center that issues a page to a mobile unit. Alternatively, the receiving mobile switching center may be an anchor mobile switching center that issues an ISPAGE2 to a boundary mobile switching center. In the general packet radio service (GPRS) environment, the receiving mobile switching center may be a gateway mobile switching center that issues an ISPAGE2 to a serving mobile switching center and a hard page to a serving GPRS support node.